Ultra high frequency generator



NOV 14, 1950 E. c. oKREss 2,530,172

ULTRA HIGH 4FREQUENCY GENERATOR Filed Feb. 17', 1945 2 Sheets-Sheet l 2719. 4. En" l IN VEN E C, ESS

ABY 'U5/@MW Nov.' 14, 1950 E. c. oKREss 2,530,172

ULTRA HIGH FREQUENCYy GENERATOR Filed Feb` 1'?, 1945 2 Sheets-Sheet 2 INVENTOR E. C /(ESS.

BY www ATTORN EY Patented Nov. 14, 1950 uNrrD SWES.r :CFFICE y Y 2,530,172 e I y SULTVRA HIGH FREQUENQY. QIINERATR; l` `"Ernest fkresfs, `lV'Iontclai'r, Lf-assignor tot e l Y 'n f Westinghouse Electric Corporation, East-Pittsf burgh, Paga corporation of Pennsylvania f Y y Application Februaryii; iegsjserialivq.57s,s7z.

*Y 12 Claims;

rl `his invention relates to ultra high frequency generators and more particularly to thetypegenerally known as magnetrons. I Magnetrons are more commonly of xed or monochromatic wave length. VSmall variations f inthe applied ieldswill alter the frequency slightly but suchA meager variations are inade-A quate for tuning purposes. Itis highly desirable to rprovdea magnetron'the'wave length of which is capable of being suitably variedfatwill. It is furthermore desirable to provide a single control for operator manipulation to effectV the tuning 'and to use a control requiring minimum attention and effort to 4c'iperateand which will remain fixed until-the operator makes a further adjustmentrthereof. vIt isan advantageous feature to have analmostproportionate change in wave length with the mechanicalv change of the adjustable part, that is, as near linear as possible. For a given cutputjas small an overall size'of device as possible is wantcdflt is sought to have a magnetron that Will' operateat as loW a voltage as possiblewfor desired output and to maintain this voltage over the' complete tuning range of the tube. `Provision of a magnetron and tuning means as-part' thereof which are fool proof and of a character which will not readily become damagedin use nor have Vpossibility of (vlieg-'402 endangering the operator using the same. j Also,l

it is desirable to 'have a magnetron operate in as -low a magnetic Viield as the mass to a minimum'.

In its general aspect, therefore, Athe invention has Vfor its objects the-accomplishment ofthe possible so as to reduce several desiderata'given above. I

More specifically, the invention is directed to the accomplishment'of the desiderata Yenumerated by specific arrangement, construction and relationship `of parts herein shown and described. ,l

These and further objects of the'inventionwill appear to those skilled in the art to which the invention appertains as the description proceeds, both by direct recitation thereof and by implif cation from the context.

"Referring to the accompanying drawings vin which like-numerals :of reference indicate similar parts throughout theseveral views; Figure 1 is a view looking atv the output end of -a magnetronembodying myfinvention; `Figure 2 is a' plan looking inthe direction of the arrows shown in conjunction with line HIJ-III of'ligl;l Figure 3 is anenlarged sectionaliview on line` `Figures 5 and 6 are sectional views on lines vV- VLand VI- V Iv respectively of Fig. 3; Figure? is alongitudinal sectional View ofthe cathqde; j Ef'gu're 8 is a'plan ofthe anode shell with cover plate removedand showing the vanes and cavitiesthereinas well Vas the straps at the near ends off the vanes; Figure'9 is a perspective View` of broken away portions of thevanesat the parts thereof preparedv for strapping; and

f Figure 10 is a perspective view showing rela.- tionof the magnetron straps 'in use. H In thej specic embodiment of the invention illustrated inV saiddrawingsythe reference nu.- meralY I0 designates the body portion, known as the anode,"of themagnetron. This anode iscomposed primarily of a Vane structure such as shown inapplications Serial No. 460,376, filed Octoberl, 1942, Vnow U. S. Patent'No. 2,520,955, granted Aseptember 5, i950,v and serial No. 462,132, filed' October 131942,* and'b0thassigned to the saine assign-ee as the present application. Said anode isconriprisedof` a substantially cylindrical me'-r tallic Shell within which'are partitions or radial vanesfl I-projecting fromV the shellinwardly to a central cathode chamber or interaction space I2; These vanesform a circular' series of trapezoidal or fpie shaped cavities` I3 Vhavinglongitudinal aperturesfld which open kinto the interaction spaceVIZ. The vanes `are ofl Vless length indirection -parallel to the axis' than the length'of the 'sh'ellso'fthat' end chambers AIliiare formed' in the shellinthe regions beyondthe ends of the vanes 'andclosed n-byf end"- covers I6 which overlie the ends of `theshell and which*v are vacuum sealed thereto. 'The'cavities I3 between the vanes open into the endV chambers I5.' These lend chambers' provide a means for lelectro-magnetic coupling betweenV the cavities I3 to permit oscillation of theftube in'its principal mode which is known inl the art as then mode of the rst multiple, At the ends of the vanes I I and adjacent the in tractionspace I2 are provided at each end of the anodedouble ring straps, identied as outer or larger 'ring I Ia 'and inner or smaller ring I Ib. 'Iuhe'purpose of these rings is to achieve large mode separationib'etwen the desiredv or 1r mode and the lower order modes, and destruction Aof these lowerprders 'Saiddestruction of the lower ordersf'ofjlmodes is accomplished bythe use of breaks'i'in certainV straps. `For instance, in Fig-v rires' fl, ySfani'lil'strap break .I la is providedgin` the upper; larger strap- II aglwhereas vstrap. break IIb ismadeinlower innerstrap I'Ib. The breaks are positioned at 90 apart. It will also be noted that the vanes are notched or stepped for reception or passage of the straps, and that the straps each alternate in engagement with the vanes and that vanes engaged by one strap of the pair at one end of the anode are skipped by the other strap of the pair, as can be readily understood from inspection of the step arrangement for the straps in Figure 9 and from the cross section of steps and straps in Figure 4. End chambers or interaction space l2 obtains coupling of the iields of the several cavities I3 so they act as if they were a single cavity, and tight coupling thereof is further promoted andassured by provision of the said straps. p

Into the covers, coaxial therewith, are sealed the ends of ferro-magnetic pole pieces I8 of a horseshoe magnet I8 which establish the required magnetic iield for proper operation of the magnetron. The pole pieces I6' are coupledrto the magnet I8 by means of pole shoes I9 which are split as shown to provide a rotatable engagement on the pole pieces without materially changing the reluctance of the magnetic circuit. The magnet I8 is anchored in proper position and orientation by a lag screw 2U whichpasses through the middle of the magnet and terminates in a stud 2i on the magnetron shell in a hole provided for the purpose. The stud is vacuum. sealed to the shell.

The magnetron anode I is provided with an output coupling device 22 vacuum sealed thereto and which couples the line to the magnetron by means of coupling loop 23 in one of the cavities I3.' The said device 22 is coupled to a coaxial line (not shown) by a mechanical coupler 24a. It will be noted that the output device with its center conductor a continuation of loop 23 and outer conductor 24 coaxial therewith and connecting between the anode body and said coupler 24a, constitutes a coaxial line. The electromagnetic energy from the magnetron passes through Vthe low loss glass seal 25 of the output device 22 into the coaxial line system.

The feed for the cathode is obtained as usual by cathode leads 26 Vacuum sealed through and insulated from the shell of the magnetron anode. The leads of the kcathode structure are terminated by non-magnetic metallic links 2l which support the. cathode structure. One link 2l, 'shown as the upper one in the drawings, connects with the lament 28 of the cathode 29 by an eyelet arrangement. and the other link connects'to both the cathode sleeve 29 andA the associated end of filament 28. The outside of saidrcathode sleeve is of course madeto be electron emissive,

The cathode 29 is terminated at each end by a non-magnetic metallic hat or disk 30, here shown as of washer shape. The iilament 28 is terminated at one end in an eyelet projecting from hat 30 and is therefore directly connected thereby to the cathode sleeve 29. At its other end, the iilament is insulated from the hat there- -at to thus avoid short circuiting the lament. For this purpose an insulating bushing 3l is seated in the end of the cathode sleeve with a shoulder portion beyond the end and separating the link and hat by being interposed therebetween and separating the iilament and cathode sleeve as well. The end portions ofthe filament are 'straight and axially aligned and situated in long eyelets 32. The lower one of these eyelets is secured to the lower one of the hats, whereas the upper one of the eyelets passes through the insulating bushingV 3| and is kept'free of contact f from the output,

4 thereby from the hat. A shorter eyelet 33 is applied or telescoped over the long eyeletand spot welded thereto and in engagement with the bushing at this end of the cathode, and it is to this eyelet that the link 21 for that end of the cathode is attached. Insulating bushing 3| may be peripherally grooved and the sleeve held thereto by crimping it into the groove.

Projecting from the anode body .is a tuner assembly 34 here shown as diametrically opposite This tuner assembly is com- 'prised of a vacuum sealed coupling device 35 vbetween its center conductor 3l and outer conductor 38. The coupling device constitutes a coaxial line, and is connected to the tuner which alsooccnstitutes a coaxial line system with outer and inner conductors 39, 4,0, but which is capable of providing various impedances tothe magnetron l0 by means of coupling device 35.

The variable reactance, which is of course part of the impedance, is obtained by varying the length of the tuner by means ofv a movable piston 4I situated in the outer .conductor 40. The piston has two invertedcoaxial quarterwave lines 42 and 43 which provideat their ends at the vgaps 44 and 45, a very high impedance. This high impedance is reiiected asa virtual electrical short circuit at gaps 46, 41 ata quarter wavef distance from the first said gaps 44 andi45.

The piston is composed of a head 48 to which is attached a cylindrical sleeve 49 which supports and generates the two coaxial Vshorted lines 42, 43 in commotion with` coaxial sleeves 50 and 5| terminating away from the piston head in a transverse cap 52. The cap 52 is spaced for enough` from head 4B to provide bothrfor the quarter wavelength of sleeves 50, 5l and for intercommunicating spaces 53, 54 between ends of the said sleeves and ysaid head. The spac- Y ing 55, 56 between sleeves 50, 5 Iand the outer and inner conductors respectively are made as small as possible in order to reduce the voltage drop between these sleeves and conductors. Spacing 55 between the outer sleeve andouter conductor provides aforementioned gaps 44 and 46 at the far and near ends thereof respectively, and spacingA 56 between the inner sleeve and iii-.- ner conductor provides aforementioned gaps'45 and 4l at the farand nearY ends thereof respectively.v The terms far .and near asjust used have reference-to relatiolof the gapsto the magnetron.

The, piston is'moved'by means `of anoncw .screw 5l at the far. side, of .they pistonhead from the magnetron and coaxial withandgu'pon the end portion'offthe Vinner conductor which is at least in part within said hollow screw.`V` Said hollow screw is longitudinallyslotted as atY 51a at opposite sides thereof and is. held from rotation by alignment means such as transversei screws 5B pin-like inner end portions v`of .which project into said slots. The hollow screw` 5l projectsfrom the end of the outer conductor and has a nut 59 on the projecting end, said nut being. heren-shown as knurledfor `finger operation. The nut is rotatable but held from 4longitudinal displacement with respect to the said .outer conductor .by .inclusion between portions of a bracket 60,*.onepart of which is in the end oi the .said conductor and secured therein as by screw 6l. `Rotation; of nut 59 will accordingly move/the-hollowscrew longi- `tudinally, andas said screw is made fast to the piston head, said piston will be correspondingly moved. The arrangement likewise functions to hold the-piston in a fixed position until an op- .erator chooses to rotate the nut. Desired adjustment is thus effected by a simple and readily applied one-hand operation, and the setting made is retained until manually altered.

(The center conductor 40 is composed of three sections; namely, at one end provides a section 162 having contact ngers, provides amiddle section or rod 63, and provides at the other end an aligning sleeve 64. The purpose of the fingered section 62 is to provide, by splitting the section partway, a plurality of resilient lingers which .will make rm mechanical and good electrical contact with the center conductor 31 of the -magnetron output coupling v35. The aligning sleeve 64 has an annular channel 65 which, in

yconjunction with the other elements of center glass.

The magnetron system described herein can bedikened Vto a three-coupled circuit in which two are resonant cavities and the third a low Q v.coupling device. The properties of such a device Ycan be derived on the basis of an orthogonal function method. The `resonant cavities are those formed by the tuner line 66 and the magnetron 'cavities (which being tightly coupled are treated as-a whole), and the low Q coupling device is Vcomprised by coupling device 24 to the load. The frequency of the magnetron varies as the piston di is moved because the length of theline 66 introduces into the magnetron' cavity for a given magnetron mode, an impedance which is in ef- `fect the equal of the ratio of the square of the product of the angular frequency and the mutual inductance and inversely as the impedance of the line 66. The orthogonal function methodk referred to adequately explains the repetitive characteristics of such a complex device.

I claim:

l., .A magnetron having a series of tightly coupled cavities therein and having exterior tuning means operable over a wide band of frequencies, said tuning means comprising a coaxial line having a coupling loop within and midway of the length of and transverse to one cavity of said device, and a movable piston in said line movement whereof changes the reactance in the coaxial line and the impedance in the entire said series of cavities in the magnetron.

2. A magnetron having tuning means operable over a wide band of frequencies, said tuning means comprising a coaxial line coupled into the magnetron, said coaxial line providing inner and outer conductors, a movable piston in said coaxial line, and means constituting part lof said piston but out of direct contact with and thereby forming gaps with said conductors and having a quarter-waVe-length dimension from the gaps, which means presents a virtual short circuit across the gaps at all piston positions and sets Y up desired impedance to the magnetron.

3. A tuning means for a magnetroncomprising a coaxial line having innerand outer conductors, a tuning piston in said outer conductor ,and girdling said inner conductor, said pistonhaving a hollow screw projection from the outer conductor and receiving the inner conductor slidably therein, and a threaded member beyondthe end of the outer conductor on said hollow screw rotatable thereon, and means in the pathpof and limiting axial displacement of` saidA member whereby rotation of said member moves the screw and piston longitudinally. 4. A tuning means for a magnetron comprising al coaxial line having inner and outer conductors, means on the inner conductor locating the same at xedlongitudinal position with respect toV the outer conductor, a tuning piston in said outer conductor and girdling said inner conductor, said piston having a hollow screw projecting from the vouter conductor andreceiving the innerconductor slidably therein, and a threadedV member beyond the end of the outer conductor on said hollow screw rotatable thereon, andmeansin the path of and limiting axial displacement of said member whereby rotationof said member moves the screw and piston longitudinally. g

5. A magnetron providing va series of resonant cavities tightly coupled electrically whereby the series oscillates as a single resonator at a frequency common to all said cavities, a cathode common to all of said resonant cavities, tuning means coupled into said resonator, an output means coupled in said resonator, said tuning means more closely following the contour of the resonator wall adjacent thereto and in closer proximity thereto and thereby being more tightly coupled electrically to the resonator than the outputmeans, whereby pull of the tuning means on resonant frequency in the resonator exceeds pull of the output means thereon. t

6. A magnetron providing a series of resonant cavities tightly coupled electrically whereby-the .series oscillatesas a single resonator at a frequency common to all said cavities, a cathode common to all of said resonant cavities, tuning means having a loop in one of said cavities, output means having a loop in another of said cavities thereby coupling the output means in said resonator, Vand the loop of the tuning means having greater surface area in its cavity than surface area of the output loop in its cavity and more closely following the contour of the adjacent Ywall of its cavity and in closer proximity to said wall than said output loop thereby providing tighter electrical coupling of the tuning means to the resonator than the electrical coupling of the output means to the resonator, whereby pull of the tuning means on the resonant frequency in Vthe resonator exceeds pull of the output means thereon.

'1. A magnetron having an anode with radial vanes dividing the interior of the anode into a plurality of cavities radiating from a central cathode chamber, a cathode in said cathode chamber, exterior tuning means, and a loop in one of said cavities connected to said tuning means, said loop having a contour substantially the shape and size of the cross-section of the cavity in which located, at the plane of said loop, whereby the loop is in close proximity to the walls of the cavity for intercepting lines of force passing through said cavity and loop.

-8. A magnetron having an anode with radial vanes dividing the interior of the anode into a plurality ofv cavities radiating from a central cathode chamber, said magnetron providing interaction `chambers :at 'the ends of fthe `cars/ities and cathode lcham'ber, la: strap 'electrically connecting dalternate lvanes fat -the ends Vvthereof `next one interactionchamber, and another strap at the same 'endsof 'the lvanes electrically connecting the intervening `vanes to each other, one of said straps beingcontinuous andthe other having a transversebreak therein interrupting the circular seriesconnection of the vanes by the strap having` 'the break therein.

9. A magnetron Ahaving an anode with radial vanes dividing the interior VVof .the anode into a plurality of cavities radiating from a central cathode chamber, said magnetron providing interac- 'tion fchambers at the ends of the cavities and cathode chamber, pairs of straps at the ends of vsaid vanes, one pair being in one interaction chamber and the other pair being in the oppo- Jsi'te vinteraction chamber, and one strap of each -pair electrically connecting alternate vanes at the l.ends thereof and the other strap of each pair `electrically connecting the intervening vanes to Jeach other, one strap of each pair being continuons and the other one of each pair having a transverse -break therein interrupting the circular series connection of the vanes by the strap having the break therein.

I10. A magnetron having an anode with radial vanes dividing the interior of the anode into a plurality ofcavities radiating from a centralcathode chamber, said magnetron providing interaction chambers at the ends lof the cavities '-andcathode chamber, pairsof straps at the ends of said'vanes, one pair being in one interaction 'chamber andthe other pair being in the opposite interaction chamber, and one strap of each pair 'electrically connecting alternate vanes at the ends thereof and the other strap of each pair elec- =trical-lylconnecting the intervening vanes to each other, one strap of each pair Vbeing continuous and Ythe other one of each pair having a transverse break therein interrupting the circular series -connection of the vanes by the strap having-the break therein, one said break being at 90 lrotated from the other.

11. -A-cathode comprising `an externally emissive sleeve, a heater filamentk in said sleeve projecting from the ends thereof, washer-like disks at the ends of and transverse to the sleeve, an insulator *inserted v1through one said disk and 'having 4fa portion in said -`sleeve, along eylet through the .insulator projecting axially there- `from, and another eyelet telescoping on the prog'ecting vend Lof the rst mentioned eyelet and secured:thereto and fixing said veyelets, to the insulator, and alead-in connection secured tothe l'outer telescoped eyelet.

12. A cathode comprising an externally emissive sleeve, `a heater filament in said sleeve projecting yfrom the ends thereof, Washer-like disks atthe -endsoi and transverse to said sleeve, an :eyelet secured to one fof said disks and to thelament, :an input lead connected to said disk to 'which the eyelet'isattached, an insulator inserted through the other disk and having a portion in `said sleeve, fa long eyelet through the insulator -projecting axially therefrom, and a short eyelet Atelescoping on the -end of the long eyelet projecting from thelinsulator and secured thereite, -a-nd ta lead-in connection secured to the outer telescope'd eyelet.

ERNEST C. OKRESS.

aannames-s .CITED rThe '-follow'ing references are of record inthe ie of this patent:

.UNITED STATES PATENTS Number VName Date Y .2,186,101 Fritz Nov. 8, 1938 2,242,888 Hollmann May 20, 1941 2,280,824 :Hansen etal Apr. 28, 1942 `.2,305,Fi81 Helbig Dec. '22, v1942 V2,233,263 Linder Feb. 25, 1944 32,348,986 Linder May 16,1944 2,351,895 .Allerding June 20, 1944 '2,408,234 .Spencer Sept. 24,1946 2,468,235 Spencer Sept. 24, 1946 ,2,413,385 Schmidt Dec. 31, 1946 2,414,085 Hartman Jan. 14, 1947 2,416,899 Brown,l Mar. .4, 1947 `2,418,117 Hale et al. Apr. 1, 1947 2,4l8,469 .Hagstrum Apr. 8, 19.47 Y2,438,194 Steele, Jr., et al. Mar. 23, 1948 2,452,032 Anderson Oct. .26, 1948 2,452,056 Kather Oct. 26, -1948 FOREIGN PATENTS 'llurn'ber Country Date "509,102 Great Britain July 11, 1939 

